H. Bolt, R. Laib, G. Stöckle
2004
Citations
0
Influential Citations
4
Citations
Journal
Archives of Toxicology
Abstract
In a recent issue of your journal Bartsch et al. (1979) have stressed the urgent need for testing the carcinogenic potential of vinyl bromide which is used in the United States for manufacture of flame-resistent polymers. This postulate was based on indirect evidence of epoxidation of vinyl bromide (VBr) to the reactive bromoethylene oxide and on mutagenicity of VBr in bacterial test systems. Furthermore, we have described alkylation of proteins (Bolt et al., 1978) and of nucleic acids (Ottenw~ilder et al., 1979) by metabolites of VBr. Interim results of a current carcinogenicity study on VBr in rats point to an increase in the incidence of hepatic angiosarcomas and of Zymhars gland carcinomas (Huntingdon Research Center, 1978). In the newborn rat, hepatocytes are very susceptible to the oncogenic effect of vinyl chloride (Maltoni, 1977). This effect can be quantitatively assessed by evaluation of pre-neoplastic foci of hepatocellular nucleoside-5'-triphosphatase ("ATPase") deficiency (Laib et al., 1979). To compare vinyl chloride (VC1) and VBr in this respect, newborn Wistar rats were exposed, together with their mothers, from their first day of life on, to 2000 ppm either VCI or VBr for the periods indicated in Fig. 1. Exposures were 8 h/day and 5 days/week; concentrations of exposure were routinely checked by gas chromatography. A third control group was not exposed. Two weeks after cessation of exposure the animals were sacrificed and the livers taken for histochemical evaluation of "ATPase"-deficient foci. All the experimental details were as previously described when comparing the effects of VCI and trichloroethylene (Laib et al., 1979). Figure 1 shows the quantity of pre-neoplastic hepatic foci induced by both VC1 and VBr. From these data an obvious oncogenic potential of VBr on the hepatocyte of the newborn rat can be inferred which is about 1/10 that of VC1. This may be viewed along with the lower rate of metabolism of VBr in rats in vivo, compared with that of VCI (Filser and Bolt, 1979). Detailed data on occupational exposure to VBr are not available at present. However, one of the VBr using US companies has reported (Chemical Week, Nov.